Interesting post by fishter from kzn..What to look for in a Fish Finder Display The 3” to 4” displays are great for reading temperature and depth information, but that is about all. Whereas the 5” screen will allow you to start correctly interpreting the difference between clutter (noise), baitballs, fish and bottom structure such as reef, coral, wrecks and other man made objects.

The reason I say this is because in order to identify and interpret the returns from your sonar you need / clarity / sharpness, or resolution as it is known. Resolution is measured in pixels, in other words - how many vertical ‘dots’ does the screen have. The reason I only mention Vertical Pixels is because we are talking about depth after all – top to bottom i.e Vertical. Horizontal means very little as it merely ‘history’, i.e – what we have already passed over. Here is a chart that clearly shows how important vertical pixels are when it comes to resolution:-

What this chart is telling us, is that a single dot on a screen with 100 vertical pixels represents an object 6” / 15.24cm high at a depth of 50ft. So if you were jigging in lets say 60m, a single dot would represent a fish height of nearly 60cm / 0.6m. Something a little bigger than this:-

You might be thinking, “I’ll just keep my eyes peeled for those single dots then.” Unfortunately there will always be some kind of clutter, and now the problem comes that there is no way of telling the difference between clutter and fish. How often have you looked at your fishfinder out at sea and thought “Is that really fish or not?” At 240VP a fishfinder actually becomes a Fish Finder, albeit difficult to interpret with a 50/50 success rate. And that is as long as your system is set up 100%. The slightest misalignment of the transducer or incorrect setting could throw these odds way down to 80/20 against you, if not worse.

480 VP on a 5” screen seems to be the perfect combination between size and resolution, giving high definition and great target separation between fish/fish and fish / structure.

There are some 5” screens out there that have 640 vertical pixels, and at the time I thought it’s a case of more is better, I was wrong. When you have too many pixels on a too smaller screen, the fish you are targeting become these tiny little ‘high definition’ dots that you cannot interpret unless you zoom in and out all the time. And that is just annoying.

Buying a ‘depthfinder’ for R1500 just to say that you have ‘electronics’ on your ski is not worth it – rather save up another few hundred Rands and get yourself a true FishFinder.